Chemical Reactions and Their Telltale Signs

The video tutorial discusses chemical changes and properties, emphasizing that chemical reactions result in new substances with different properties. It highlights four signs of chemical reactions: gas formation, unexpected color change, precipitate formation, and temperature change. Each sign is explained with examples, such as bubbling indicating gas formation and color change showing a reaction. The tutorial concludes by inviting students to ask questions and engage in further discussion.

What happens to the properties of substances when a chemical change occurs?

• They become less reactive.

• They change completely.

• They become more volatile.

• They remain the same.

Which of the following is NOT a chemical property?

• Flammability

• Corrosion

• Melting

• Rusting

What is a sign that a chemical reaction has occurred when mixing two liquids?

• The liquids become colder.

• A gas forms unexpectedly.

• The liquids become thicker.

• The liquids separate.

What does an unexpected color change in a reaction indicate?

• A phase change

• A physical change

• A chemical reaction

• A temperature change

What is formed when two clear liquids react to create a cloudy mixture?

• A gas

• A precipitate

• A solution

• A vapor

What is the term for a solid formed from a chemical reaction in a liquid?

• Sediment

• Precipitate

• Residue

• Deposit

What might you observe if a chemical reaction causes an unexpected temperature change?

• The reaction produces sound.

• The reaction becomes warmer or cooler.

• The reaction becomes visible.

• The reaction emits light.

What happens when the liquid in an ice pack mixes with the solid crystals inside?

• The pack emits light.

• The pack changes temperature.

• The pack changes color.

• The pack becomes solid.

Which of the following is NOT an indicator of a chemical reaction?

• Formation of a precipitate

• Unexpected color change

• Unexpected gas formation

• Dissolving of a solid

What is a common use of the unexpected temperature change indicator in everyday life?

• Lighting a match

• Ice packs for injuries

• Boiling water

• Cooking